In 1817, the Scottish optical scientist David Brewster submitted a patent for a kaleidoscope, a word he invented. It went on to great success within only a few years, spreading the word far and wide. But where did Brewster get the word from? He created it from joining two Greek words: kalos, meaning "beautiful", and eidos, meaning "shape", obviously so named because of the pretty patterns formed when one looks through a kaleidoscope (additionally, -scope is just a suffix, influenced by telescope, meaning "examine"). Kalos sounded something like kalwos in what was most likely Proto-Hellenic, and in Proto-Indo-European it took the form of kal, also defined as "beautiful". Meanwhile, eidos derives from the reconstructed PIE root weydos, meaning "to see" (this developed from "shape" to "image" over time before ultimately settling on that).
Adam Aleksic, a freshman studying linguistics at Harvard University, has been described as the internet's sixth most famous etymologist. He has disturbing interests in words, vexillology, geography, board games, limericks, and law, and he loves writing about himself in the third person.
The Etymology Nerd